The present invention relates to an ultrasonic pulse transmission method and an ultrasonic diagnostic apparatus, and more particularly to an ultrasonic pulse transmission method and an ultrasonic diagnostic apparatus that can prevent noticeable interleave blocks on a display screen.
Japanese Patent Application Laid Open No. H3-126442 discloses an interleaving scanning technique involving, when a number of packets P (≧2) is defined for conducting P ultrasonic pulse transmissions in one direction to acquire one acoustic line signal, interleaving an ultrasonic pulse transmission for acquiring a different acoustic line signal between the ultrasonic pulse transmissions in the one direction.
When the number of ultrasonic pulse transmissions in the different directions interleaved between the ultrasonic pulse transmissions in the one direction is defined as (I−1), I is referred to as the number of interleaves. I is defined as I≧2.
As an example, if the number of packets P=2, the number of interleaves I=3, and one frame is composed of acoustic lines lined up in a sequence of acoustic line 1, acoustic line 2, acoustic line 3, acoustic line 4, . . . , then ultrasonic pulse transmissions are done in the following order:
acoustic line 1-acoustic line 2-acoustic line 3-acoustic line 1-acoustic line 2-acoustic line 3-acoustic line 4-acoustic line 5-acoustic line 6-acoustic line 4-acoustic line 5-acoustic line 6-acoustic line 7-acoustic line 8-acoustic line 9-acoustic line 7-acoustic line 8-acoustic line 9- . . .
In this example, interleaving is achieved by unitary acoustic line groups each comprised of the number of interleaves of adjacent acoustic lines, such as acoustic lines 1-3, acoustic lines 4-6, acoustic lines 7-9, and so forth. These acoustic line groups, each of which serves as a unit of interleaving, are called interleave blocks.
Since the conventional interleaving scanning conducts interleaving within one frame, the one frame is constituted by concatenating a plurality of interleave blocks.
However, the difference in scan time between acoustic lines at a boundary of adjacent interleave blocks is larger than the difference in scan time between acoustic lines within an interleave block, which leads to a problem that difference in image quality occurs across interleave blocks, resulting in noticeable interleave blocks on an image.